The field of the invention is cell-specific expression of proteins.
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a 22-kDa protein originally purified from the conditioned medium of macrophage-like U-937 cells. The human gene encoding HB-EGF has been cloned (Fen et al., 1993, Biochemistry 32:7932-7938), and is organized into six exons spanning approximately 14 kb. The mature processed peptide contains at least 86 amino acids and is a potent mitogen and chemoattractant for vascular smooth muscle cells but not endothelial cells (Higashiyama et al., 1992, J. Biol. Chem. 267:6205-6212; Higashiyama et al., 1993, J. Cell Biol. 122:933-940). Expression of HB-EGF is regulated by cytokines in vascular endothelial cells (Yoshizumi et al., 1992, J. Biol. Chem. 267:9467-9469) and by phorbol esters, angiotensin II, and thrombin in vascular smooth muscle cells (Temizer et al., 1992, J. Biol. Chem. 267:24892-24896; Dluz et al., 1993, J. Biol. Chem. 268:18330-18334; Nakano et al., 1993, J. Biol. Chem. 268: 22941-22947). HB-EGF also appears to be transcribed and regulated in cultured cells commonly associated with atherosclerotic lesions (Ross, R., 1993, Nature 362:801-809; Schwartz et al., 1990, Physiol. Rev. 70:1177-1209), but the molecular mechanisms regulating transcription of this gene have not been defined.